位置信息包示例对我不起作用Flutter

Question

我是新手，尝试从移动应用获取当前位置经纬度，因为我正在使用位置1.4.1，还找到了我在下面的链接中提到的示例，我做了如何他们提到了逐步的过程，但仍然存在抛出错误。

Please go through example

Exception has occurred.
PlatformException(PERMISSION_DENIED, The user explicitly denied the use of location services for this app or location services are currently disabled in Settings., null)

这是我在运行代码时遇到的异常，但是在该示例中有一个尝试获取PlatformException的尝试。我被困在这里，请帮帮我，谢谢。

我的AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.latlong">

    <!-- The INTERNET permission is required for development. Specifically,
         flutter needs it to communicate with the running application
         to allow setting breakpoints, to provide hot reload, etc.
    -->
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

    <!-- io.flutter.app.FlutterApplication is an android.app.Application that
         calls FlutterMain.startInitialization(this); in its onCreate method.
         In most cases you can leave this as-is, but you if you want to provide
         additional functionality it is fine to subclass or reimplement
         FlutterApplication and put your custom class here. -->
    <application
        android:name="io.flutter.app.FlutterApplication"
        android:label="lat_long"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <!-- This keeps the window background of the activity showing
                 until Flutter renders its first frame. It can be removed if
                 there is no splash screen (such as the default splash screen
                 defined in @style/LaunchTheme). -->
            <meta-data
                android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
                android:value="true" />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>
</manifest>

main.dart：

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:location/location.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Map<String, double> _startLocation;
  Map<String, double> _currentLocation;

  StreamSubscription<Map<String, double>> _locationSubscription;

  Location _location = new Location();
  bool _permission = false;
  String error;

  bool currentWidget = true;

  Image image1;

  @override
  void initState() {
    super.initState();

    initPlatformState();

    _locationSubscription =
        _location.onLocationChanged().listen((Map<String,double> result) {
          setState(() {
            _currentLocation = result;
          });
        });
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  initPlatformState() async {
    Map<String, double> location;
    // Platform messages may fail, so we use a try/catch PlatformException.

    try {
      _permission = await _location.hasPermission();
      location = await _location.getLocation();


      error = null;
    } on PlatformException catch (e) {
      if (e.code == 'PERMISSION_DENIED') {
        error = 'Permission denied';
      } else if (e.code == 'PERMISSION_DENIED_NEVER_ASK') {
        error = 'Permission denied - please ask the user to enable it from the app settings';
      }

      location = null;
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    //if (!mounted) return;

    setState(() {
        _startLocation = location;
    });

  }

  @override
  Widget build(BuildContext context) {
    List<Widget> widgets;


    if (_currentLocation == null) {
      widgets = new List();
    } else {
      widgets = [
        new Image.network(
            "https://maps.googleapis.com/maps/api/staticmap?"+
            "center=${_currentLocation["latitude"]},${_currentLocation["longitude"]}"+
            "&zoom=18&size=640x400&key=AIzaSyBw_T2wCQGqWBEdF4UzMAuoQX_DCemYpQw")
      ];
    }

    widgets.add(new Center(
        child: new Text(_startLocation != null
            ? 'Start location: $_startLocation\n'
            : 'Error: $error\n')));

    widgets.add(new Center(
        child: new Text(_currentLocation != null
            ? 'Continuous location: $_currentLocation\n'
            : 'Error: $error\n')));

    widgets.add(new Center(
      child: new Text(_permission 
            ? 'Has permission : Yes' 
            : "Has permission : No")));

    return new MaterialApp(
        home: new Scaffold(
            appBar: new AppBar(
              title: new Text('Location plugin example app'),
            ),
            body: new Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: widgets,
            )));
  }
}

和我的pubspec.yaml：

name: lat_long
description: A new Flutter project.

dependencies:
  flutter:
    sdk: flutter

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.2
  location: ^1.4.1

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://www.dartlang.org/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.io/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.io/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.io/custom-fonts/#from-packages

Answer 1

我在少数Android设备上也遇到了同样的问题。但是我已经找到了它-

您需要做的就是设置Geolocator（）.. forceAndroidLocationManager = true的值。

最终Geolocator geolocator = Geolocator（）.. forceAndroidLocationManager = true;

Answer 2

在您实际获取位置/权限之前，您只是遇到了错误的顺序。

从您的onLocationChanged()中删除initState()订阅，并将try中的initPlatformState()语句更改为：

try {
      location = await _location.getLocation();
      _permission = await _location.hasPermission();

      _locationSubscription =
            _location.onLocationChanged().listen((Map<String,double> result) {
              setState(() {
                _currentLocation = result;
              });
            });
      error = null;
    }

请注意交换位置信息并检查是否有权限行。

编辑：添加了完整代码：

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:location/location.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Map<String, double> _startLocation;
  Map<String, double> _currentLocation;

  StreamSubscription<Map<String, double>> _locationSubscription;

  Location _location = new Location();

  bool _permission = false;
  String error;

  bool currentWidget = true;

  Image image1;

  @override
  void initState() {
    super.initState();

    initPlatformState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  initPlatformState() async {
    Map<String, double> location;
    // Platform messages may fail, so we use a try/catch PlatformException.

    try {
      location = await _location.getLocation();
      _permission = await _location.hasPermission();

      _locationSubscription =
            _location.onLocationChanged().listen((Map<String,double> result) {
              setState(() {
                _currentLocation = result;
              });
            });
      error = null;
    } on PlatformException catch (e) {
      if (e.code == 'PERMISSION_DENIED') {
        error = 'Permission denied';
      } else if (e.code == 'PERMISSION_DENIED_NEVER_ASK') {
        error = 'Permission denied - please ask the user to enable it from the app settings';
      }

      location = null;
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    //if (!mounted) return;

    setState(() {
        _startLocation = location;
    });

  }

  @override
  Widget build(BuildContext context) {
    List<Widget> widgets;


    if (_currentLocation == null) {
      widgets = new List();
    } else {
      widgets = [
        new Image.network(
            "https://maps.googleapis.com/maps/api/staticmap?"+
            "center=${_currentLocation["latitude"]},${_currentLocation["longitude"]}"+
            "&zoom=18&size=640x400&key=AIzaSyBw_T2wCQGqWBEdF4UzMAuoQX_DCemYpQw")
      ];
    }

    widgets.add(new Center(
        child: new Text(_startLocation != null
            ? 'Start location: $_startLocation\n'
            : 'Error: $error\n')));

    widgets.add(new Center(
        child: new Text(_currentLocation != null
            ? 'Continuous location: $_currentLocation\n'
            : 'Error: $error\n')));

    widgets.add(new Center(
      child: new Text(_permission 
            ? 'Has permission : Yes' 
            : "Has permission : No")));

    return new MaterialApp(
        home: new Scaffold(
            appBar: new AppBar(
              title: new Text('Location plugin example app'),
            ),
            body: new Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: widgets,
            )));
  }
}

Answer 3

我遇到了类似的问题，然后我发现这是一个编译问题，并且该应用程序已拒绝使用位置服务，您需要在终端中运行以下命令，然后您的应用程序会再次询问您您要使用位置服务：

cl_bal = pd.DataFrame(np.repeat(u, len(d_range)), index= pd.MultiIndex.from_product([currency, d_range]), dtype= int) print (cl_bal) 0 BTC 2019-06-24 5000 2019-06-25 5000 ETH 2019-06-24 10000 2019-06-25 10000 BCH 2019-06-24 1046 2019-06-25 1046

Answer 4

我注意到您已将ACCESS_FINE_LOCATION和ACCESS_COARSE_LOCATION权限都添加到了Android清单文件中。您应该使用其中之一，但不能同时使用两者。 See the docs.

Answer 5

请不要忘记检查您是否在手机上激活了地理定位